One type of material attribute monitor is a grain yield monitor. Grain yield monitors require calibration to provide an accurate record of grain yield and moisture by location across a field. Calibration may be performed, for example, when field conditions change, such as when moving between fields. This involves operating the combine in the field while manually collecting yield monitor data, weighing the harvested grain on a scale, testing a sample for moisture content, and then applying a correction based on actual grain attributes versus the sum of those measured by the yield monitor. This approach has two major drawbacks.
First, this approach is a time consuming process that requires segregation of the grain by combine and manual recording of which data are associated with the grain used in the calibration process. In a word, the calibration procedure is inconvenient and consequently does not get done as often as it should. Furthermore, conditions may change within a field that should warrant a recalibration of the yield monitor. Given the difficulty of observing when recalibration should occur and the inconvenience of recalibrating, it just doesn't get done.
Second, on large scale farms, it is not unusual to have multiple combines, grain carts, and grain trucks simultaneously operating in a field at a given time. The grain co-mingles from different parts of the field as it moves from the field to the trucks. For example, a typical Illinois corn field is 80 acres in size with an average yield of 175 bushels per acre. The total amount of grain in the field is then 80*175=14,000 bushels. The combines have grain tanks of 100-200 bushel capacity. Grain carts typically receive the grain from the combines, and have a capacity typically in a range from 200-800 bushels. The grain carts then are unloaded into grain trucks. Grain trucks are typically limited to 20,000 pounds/axel, so a four axel truck would have a maximum weight of 80,000 pounds of which 20,000 are the truck itself. Corn weighs about 60 lbs/bushel, so the truck can carry 60,000 pounds or about 1000 bushels of corn. Thus, 14 truckloads of corn need to be transported from the field.
Accordingly, providing segmentation of the grain for calibration purposes by combine, grain cart, and truck has been found to be inconvenient, and inefficient.